Apparatus for filling and emptying air-cooled condensers



APPARATUS FOR FILLING AND EMPTYING AIR-COOLED CONDENSERS Filed Dec. 22,1955 L. HELLER June 23, 1959 4 Sheets-Sheet 1 INVENTOR LASZLO HELLERATTORNEYS June 23, 1959 HELLER 2,891,773

APPARATUSFOR FILLING AND EMPTYING AIR-000L120 CONDENSERS Filed Dec. 22,1955 4 Sheets-Sheet 2 INVENTOR LASZLO HELL Elk ATTORNEYS June 23, 19594.. HELLER 2,891,773

APPARATUS FOR FILLING AND EMPTYING AIR-COOLED CONDENSERS Filed Dec. 22,1955 4Shets-Sheet a INVENTOR. LASZLO HELLER BY (QM MEL/m ATTORNEYS June23, 1959 1 HELLER 2,891,773

APPARATUS FOR FILLING AND EMPTYING AIR-COOLED CONDENSERS Filed Dec. 22,1955 4 Sheets-Shae 4 INVENTOR. LASZLQ HELLER An ormeys United StatesPatent F APPARATUS FOR FILLING AND EMP'I'YING AIR-COOLED CONDENSERSLfiszl Heller, Budapest, Hungary, assignor to Licencia TalalmanyokatErtekesito Vallalat, Budapest, Hungary, :1 firm It is known in steampower plants to use mixing condensers in which the steam is precipitatedby means of the condensate serving as cooling Water and to cool againthe condensate, which has thereby been heated, in a closed system bymeans of the atmospheric air. With this object in view use is made as arule of a closed cooling system consisting of thin-Walled tubes providedwith cooling ribs in which tubes the cooling water is circulated,whereby cooling air flows between the tubes and the ribs sweeping thesurfaces of the system to be cooled.

Since in such air condensers, comparatively very large amounts of heathave to be transmitted at a very small temperature difference and smallventilator work of the atmospheric air, this means heat exchangesurfaces be tween the cooling water and the air which are of very largedimensions. In order to reduce these dimensions it is necessary to useheat exchangers of high specific capacity. The plant provided withair-cooled condensers of the kind referred to is often mounted at aplace where the temperature of the atmospheric air sinks temporarilybelow zero during the year so that in the case of the said heatexchangers of great specific capacity there is a danger that thecondensate will freeze. This danger is especially great if at the sametime as the temperature of the outer air is low, owing to a disturbance,such as the removal of the turbine load or for other reasons, the heatsupplied to the cooling surface is reduced and sinks below apredetermined value.

The flow of the condensation heat of the plant towards the heatexchangers may, due to some of the reasons above given, sink suddenly toa great extent or stop altogether, in which caseeven in spite of thestopping of the air ventilator or owing to the great specific capacityof the heat exchange surfaces-the cooling water may freeze in a veryshort time. In order to avoid this, the air condensation device must beso constructed, that all those parts thereof which are exposed to thedanger of freezing as above explained may be emptied easily and quickly,preferably automatically in the case of large plants.

The conditions are similar if the plant, or a part thereof, has to beset into operation when the outer temperature is below freezing point.As long as the turbines do not run with a sufficient amount of steam noheat will flow to the heat exchange surface which would be suflicient toprevent freezing of the cooling water. On the other hand, it is notpossible to produce the vacuum necessary for the starting of the turbinewithout a sufficient circulation of cooling water. Therefore suitablyconstructed apparatus for starting are necessary which will overcome thesaid difficulties.

The invention relates to an air condensating apparatus in which theexchange surfaces carrying the cooling water inside and being swept onthe outside by the atmospheric air are prevented from freezing in thecase of an outer temperature below the freezing point, when the amountof steam flowing through the steam turbines is reduced,

2,891,773 Patented June 23, 1959 or ceases altogether and also when theturbines are started.

The object of the invention is to prevent or reduce the freezing dangerof the cooling Water by means of an arrangement which enables a rapidemptying of the water from all parts of the apparatus which is exposedto freezing.

With this object in view, according to the invention, the coolingapparatus of the air-cooled condenser, constituted by heat exchangeelements, is provided with at least two vertical groups of tubes andwith valves associated therewith, which enable two settings to beeffected, in one of which, corresponding to the valve setting for thefilling of the apparatus with cooling water, the latter, driving theair, flows in the same direction upwards in both groups of tubes, and inthe other one corresponding to the valve setting for normal operation,the cooling water flows in opposite directions, that is to say, in theone group upwards and in the other group downwards.

Examples of construction of the apparatus according to the invention areillustrated in the accompanying drawings, in which- Figure l is across-section of an air-cooled condenser (cooling tower) according tothe invention;

Figure 2 is a diagram of connections of a part of the heat exchanger ofthe condenser shown in Figure 1;

Figure 3 is a modification of the diagram of connections of the heatexchanger; and I Figure 4 is an apparatus for accelerating the removalof the air when the condenser is filled with cooling water.

The same references are shown in all the figures with respect to thesame components.

It will be seen from the vertical section of the cooling tower shown inFigure 1', that the same consists of a base 1 on which rests the actual,preferably prismatic or cylindrical, cooler consisting of heatexchangers 2 built up of ribbed tubes. A column 3 is mounted in thecentre to support a ventilator 4, which sucks the cooling air from theoutside between the individual heat exchangers 2 in the direction of thearrows 5, pressing it in the direction of the arrows 6 into a difiusor7. The heat exchangers 2 constitute the vertical outer walls of thecooling tower.

Figure 2 shows the diagram of connections of the condenser tubes. Thesame are so arranged that in case of need, that is to say when the outertemperature is below 0 C. and when the steam consumption of the turbineis too small, the tubular system can be rapidly emptied. Moreover, carehas to be taken that the plant or a part thereof, can be put intooperationsufiiciently quickly also when the outer temperature is toolow, that is to say, that it can be filled with Water if the coolingplant has been previously emptied. Without circulation of the coolingwater the required vacuum cannot be produced in order to start theturbines, so that also in this case certain difficulties have to beovercome to avoid the freezing of the cooling water.

The exhaust steam leaves the turbine through the exhaust pipe connector8 and reaches into the mixing condenser 9, into which cooling water issprayed through one or more nozzles 10. The precipitated condensateleaves the mixing condenser 9 through the pipe 11, whereupon a portionthereof is supplied through the pump 12,

and the pipe 24 to the steam boiler (not shown in the drawing) and theother part through the pipe 25 and pump 26 to a lower collecting chamber27. In the above example of construction two pipe lines 28 ascend fromthe lower'right-hand side of the collecting chamber 27 to an uppercollecting chamber 29. With the pump 26: running, the valve 14 beingopen and the valves 16 and 17 being closed, the cooling water flowsupwards in Q both pipe lines 28 forming a group, and it returns throughpipe lines 36 forming a second group to the second collecting chamber 31lying below, then flowing through the open valve 13 and the pipe 34 tothe spraying nozzle of the mixing condenser 9.

If the plant is empty and has to be filled with water, this cannot takeplace in the manner that is usual for instance in central heatinginstallations, in which the water circulates in a completely closed pipesystem, whereby it is possible to fill the same from below, the airescaping at one or more very high points. In the apparatus according tothe invention the pipe system, which is otherwise completely closed, isinterrupted by the mixing condenser, so that a filling up is possibleonly through the pipe 25, namely by means of the pump 26. In the case ofsuch filling, however, the cooling water may drag along with it the airthat has collected in the collecting chamber 29, so that it reaches thepipe lines Where it disturbs the water circulation which, in normaloperation, is directed downwards, causing the water to freeze in some ofthe pipes. it is therefore necessary to provide such a connection of thepipe lines that when the filling takes place the cooling water flows inall pipe lines 28 and 30 upwards. Moreover, care has to be taken, thatafter the completion of the filling the connection of the pipe lines canbe switched again to the normal operation, whereby the cooling waterwill again flow in the pipes 23 only upwards and in the pipes 343 onlydownwards. For this purpose, the valves 13 to 17 are provided whichenable, in case of need, the mixing condenser 9 to be disconnected fromthe circulation of the cooling water.

For the filling of the system, which is efifected by means of the pump26, the valves 13, 15 and 17 are closed and the valves 14, 16 and 18 areopened. By closing the valves 13 and 17, the path of the cooling waterfrom the pipe system to the mixing condenser 9 is closed, and likewiseby closing the valve 15, the flow to the collecting vessel 21, which isused when the pipe system is being emptied, is interrupted. By openingthe valves 14 and 16 the flow from the pump 26 to all the pipe lines 28and 311 is opened from below, and by opening the valve 18 the path forthe removal of the air from the pipe system is freed. Thus, the coolingwater ascends in all the pipe lines simultaneously upwards and pressesthe air in front of it through the valve 18 into the open. After theremoval of the air, the valve 13 has to be opened and the valves 16 and18 have to be closed (the valve 14 remaining open and the valves 15 and17 remaining closed), whereby the normal working condition is attained.The cooling water flows in the pipe lines 28 upwards and in the pipelines 30 downwards.

If the emptied plant has to be set into operation in cold weather, thewhole of the amount of water that is to be supplied to the pipe systemhas to be correspondingly preheated before the heat exchangers arefilled up and the water circulation is started. For this purpose, aseparate pipe line 32 is provided in the arrangement according to Figure2, through which steam can be supplied to the mixing condenser 9 from asuitable point through a valve 33. After the valve 33 has been opened,the pump 26 is started, the valve 17 is opened and the valves 13 and 14are closed. The water is drawn through the pump 26 and the pipe 11 fromthe mbring condenser and is pressed again into the mixing condenserthrough the pipe 25, valve 17, pipe 34 and nozzle 11). This circulationof the Water is continued until the water in the mixing condenser and ina storage container, which may be connected in parallel with the mixingcondenser, has reached the desired temperature, whereupon the filling upof the pipe system of the cooling plant is effected in the mannerdescribed.

The emptying of the heat exchangers is effected by closing the valves 13and 1 and opening the valves 15, 16 and 18. The water then runs out ofthe pipe system of the heat exchangers through the valve 15 and the pipe19 into the collecting container 21, whereby the air flows after itthrough the valve 18.

The construction shown in Figure 3 likewise shows an air condensationapparatus, which differs from the one in Figure 2 by that in all thepipe lines 35 of the heat exchangers, in normal operation, the coolingwater flows in the same direction, that is to say, from below upwards.in this example of construction, a collecting chamber 37 common to allthe pipe lines 35 is provided at the lower part of the heat exchanger.The upper collecting chamber 29 is connected through a pipe line 36 andthe pipe line 34 with the nozzle 10 in the mixing condenser 9. in normaloperation, the cooling water flows in the pipe line 36 downwards to thenozzle 10, through the open valve 13, whilst the valves 16, 17 and 18are closed. Moreover, for the purpose of setting for normal operation,and also for the filling up or emptying of the apparatus, the valves 13to 18 are set as above described with reference to Figure 2.

Figure 4 shows a further form of construction in which during filling aswell as during the operation, the removal of the air is accelerated orensured.

During the filling of the apparatus, with the setting of the valvesabove described, the water will flow in the pipe lines 37, 38 from belowupwards and will press the air out of the apparatus through the openvalve 18. Thereby, air accumulates in the upper collecting chamber 29.At the transition from filling to normal operation, the valve 13 isopened and the valves 16 and 18 are closed, the valve 14 continuing toremain open and the valves 15 and 17 closed. Cooling water then flowsfrom the collecting chamber 27 in the pipe lines 37 upwards and in thepipe lines 33 downwards. The flow is maintained by the pump 26. Duringthe operation, air may accumulate besides in the chamber 29 also in thechamber 31. Thereafter, such an apparatus has to be preferably freed ofair continuously also during normal working.

These two problems, that is to say the rapid removal of air duringfilling and the continuous removal thereof during operation, are solvedby the form of construction shown in Figure 4, by connecting, itpossible, the highest points of the collecting chambers 2% and 31 withthe vacuum space of the mixing condenser, through the pipes 39, 4t and41. Since, while filling the apparatus With cooling Water, a vacuum hasalready to be maintained in the mixing condenser 9, which is furtherincreased after the starting of the turbine, the vacuum produces a flowin the pipes 39, 4 3 and 41 from the collecting chambers 29, 31 to themixing condenser, whereby the air present in the said chambers isdelivered into the vacuum space of the mixing condenser, from which thesame is delivered into the open by the vacuum pump. After the removal ofthe air present in the pipe system, a continuous flow of cooling Waterto the mixing condenser is started, whereby accumulation of furtherquantities in the collecting chambers 29, 31 during working isprevented. in order to be able to adjust the amount of water flowingthrough the pipes 39, 4t and 41 to a constant value, according to theinvention, throttling discs 42 and 43 are provided in the air dischargepipes 39 and 4.9. It is well known that such throttling discs allow agreater volume of air than of water to pass per unit of time. The waterwhich is supplied to the mixing condenser via the pipe 41 may be usedthere for the condensation of the steam coming from the turbine. In thisway, this amount of water constitutes only a comparatively small loss,since a portion of the amount of water that flows through the throttlingdisc is not as yet completely cooled.

A valve 44 is provided in the pipe 41. This valve has to be closed whenthe apparatus is being emptied so that no air can reach the mixingcondenser which is under a vacuum.

As already mentioned above, the need may arise during operation for thepipe system to be completely or partly emptied. This may especially bethe case in cold weather and when the conditions of operation arechanging. If unexpectedly the apparatus fails in cold weather, then thewhole of the pipe system has to be emptied as soon as possible. However,it may also be necessary to empty the pipe system only partly, forinstance, in the case of full load and especially very cold weather, orin the case of partial loading and an outer temperature of only a fewdegrees below freezing point. In such cases the disconnection of aportion of the cooling surface prevents the dangerous cooling off of thecooling water. However, in this case one has to take care that the wateris quickly discharged from the disconnected part of the pipe system.

In order that this operation may be carried out without fail, the valve33 has been provided in the pipe 32 in the form of construction shown inFigure 2, through which valve steam is added directly to the mixingcondenser, whereby it is ensured that the temperature of the coolingwater behind the cooling elements cannot drop below a predeterminedvalue.

The valve 33 may be operated by hand or automatically. A thermometer 45is preferably provided in the pipe 34-, which, when the admissiblelowest temperature is reached, gives, in a known manner, an optical oracoustic signal, whereupon the valve 33 is opened by the operatingpersonnel. However, it is possible to derive, in a known manner, a pulsefrom the thermometer 45 by means of which the valve 33 is automaticallyoperated. By opening the valve 33 and by artificially maintaining thedesired temperature of the cooling water connected therewith, thepersonnel is enabled to disconnect a suitable number of cooling elementsand empty the same. In the case of larger plants, the emptying itselfmay also be effected automatically, in which case the pulse transmitter45 correspondingly operates, in addition to the valve 33, the otherparts which participate in the emptying of the plant.

What I claim is:

1. An apparatus for filling and emptying and for normal operation ofcooling towers of air condensers, comprising in combination a pipesystem; heat exchangers incorporated in said pipe system, said heatexchangers having a first and a second vertical group of pipes; a pumpfor circulating the cooling water in said pipe system and for supplyingcooling water to said pipe system for filling; a mixing condenser, whichthe water cooled in said heat exchangers is supplied to; a first andsecond lower collecting chamber and an upper collecting chamber, whichsaid groups of pipes of said heat exchangers open into; first pipes forconnecting the mixing condenser over said pump and over the first lowercollecting chamber with said first group of vertical pipes, second pipesfor connecting said second group of vertical pipes over the second ofsaid lower collecting chambers with the mixing condenser and third pipesfor emptying water from the pipe system; first valves arranged in saidfirst pipes and second pipes for permitting in their open positioncirculation of cooling water in normal operation through said firstgroup of vertical pipes in upward direction and said second group ofvertical pipes in downward direction and through the mixing condenser;second valves arranged in the pipe system for disconnecting the mixingcondenser from said circulation and preventing discharge of coolingwater in their closed position, during filling; a third valve forpermitting in its open position escape of air from the pipe system atthe top of the vertical pipes; said apparatus being adapted to avoidfreezing of the cooling water within the apparatus by the quick flow ofwater.

2. An apparatus as claimed in claim 1, comprising a separate pipelinefor conveying air from the heat exchangers into the mixing condenser,from which the air is removed by said pump during normal operation.

3. An apparatus as claimed in claim 2, comprising an interconnectingpipe for continuous communication between the points of the collectingchambers for the collection of air, and the vacuum space of the mixingcondenser.

4. An apparatus as claimed in claim 3, comprising throttle discsprovided in each pipe branch of the interconnecting pipe.

5. An apparatus as claimed in claim 1, comprising additional valve meansfor supplying fresh steam to the condenser in order to maintain apredetermined temperature of the cooling water which is re-cooled.

6. An apparatus as claimed in claim 2, comprising additional valve meansfor supplying fresh steam to the condenser in order to maintain apredetermined temperature of the cooling water which is re-cooled.

7. An apparatus as claimed in claim 1, comprising an interconnectingpipe for continuous communication between the points of the collectingchambers for the collection of air, and the vacuum space of the mixingcondenser and also comprising additional valve means for supplying freshsteam to the condenser in order to maintain a predetermined temperatureof the cooling water which is re-cooled.

8. An apparatus as claimed in claim 5, comprising a pulse transmitterfor automatically controlling the additional valve means in dependenceon the temperature of the cooling water.

9. An apparatus as claimed in claim 1, comprising a separate pipelinefor conveying air from the heat exchangers into the mixing condenser,from which the air is removed by said pump during normal operation, saidapparatus also comprising additional valve means for supplying freshsteam to the condenser in order to maintain a predetermined temperatureof the cooling water which is re-cooled and a pulse transmitter forautomatically controlling the additional valve means in dependence onthe temperature of the cooling water.

10. An apparatus as claimed in claim 1, comprising a separate pipelinefor conveying air from the heat exchangers into the mixing condenser,from which the air is removed by said pump during normal operation; saidapparatus also comprising an interconnecting pipe for continuouscommunication between the points of the collecting chambers for thecollection of air, and the vacuum space of the mixing condenser;additional valve means for supplying fresh steam to the condenser inorder to maintain a predetermined temperature of the cooling water whichis re-cooled and a pulse transmitter for antomatically controlling theadditional valve means in dependence on the temperature of the coolingwater.

References Cited in the file of this patent UNITED STATES PATENTS2,335,250 Adlam Nov. 30, 1943 2,356,404 Heller Aug. 22, 1944 2,360,900Setterwall Oct. 24, 1944 2,808,234 Rosenblad Oct. 1, 1957

